chore: Refactor app layout visual test definitions

[jperals]

Description

Wrap all app layout test definitions in a parent definition with "AppLayout" as description so that when run internally, they keep appearing under a group with this name.

How has this been tested?

Running in my pipeline.

Review checklist

The following items are to be evaluated by the author(s) and the reviewer(s).

Correctness

• Changes include appropriate documentation updates.
• Changes are backward-compatible if not indicated, see CONTRIBUTING.md.
• Changes do not include unsupported browser features, see CONTRIBUTING.md.
• Changes were manually tested for accessibility, see accessibility guidelines.

Security

• If the code handles URLs: all URLs are validated through the checkSafeUrl function.

Testing

• Changes are covered with new/existing unit tests?
• Changes are covered with new/existing integration tests?

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.61%. Comparing base (f97729a) to head (e49c9be).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4826   +/-   ##
=======================================
  Coverage   97.61%   97.61%           
=======================================
  Files         952      952           
  Lines       30816    30816           
  Branches    11318    11317    -1     
=======================================
  Hits        30081    30081           
- Misses        688      728   +40     
+ Partials       47        7   -40     

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